Hydrogen storage of calcium atoms adsorbed on graphene: First-principles plane wave calculations
Abstract
Based on first-principles plane wave calculations, we showed that Ca adsorbed on graphene can serve as a high-capacity hydrogen storage medium, which can be recycled by operations at room temperature. Ca is chemisorbed by donating part of its 4s charge to the empty π∗ band of graphene. At the end the adsorbed Ca atom becomes positively charged and the semimetallic graphene changes into a metallic state. While each of the adsorbed Ca atoms forming the (4×4) pattern on the graphene can absorb up to five H2 molecules, hydrogen storage capacity can be increased to 8.4wt% by adsorbing Ca to both sides of graphene and by increasing the coverage to form the (2×2) pattern. Clustering of Ca atoms is hindered by the repulsive Coulomb interaction between charged Ca atoms.
- Publication:
-
Physical Review B
- Pub Date:
- January 2009
- DOI:
- 10.1103/PhysRevB.79.041406
- arXiv:
- arXiv:0901.1942
- Bibcode:
- 2009PhRvB..79d1406A
- Keywords:
-
- 68.43.-h;
- 82.30.Fi;
- 31.15.ae;
- Chemisorption/physisorption: adsorbates on surfaces;
- Ion-molecule ion-ion and charge-transfer reactions;
- Electronic structure and bonding characteristics;
- Condensed Matter - Mesoscale and Nanoscale Physics
- E-Print:
- 5 pages, 3 figures